Blender won't finish rendering
As said by Bithur in the comments, it is quite possible that you are rendering an animation. Stop the current render with the Escape key. Then press F12 (make sure that you don't press Control+F12 by accident!), or go to Render -> Render Image from the toolbar.



If it continues to do the same, go into the render settings and make sure that Sampled motion blur is unchecked. If even this doesn't help make the render finish, uncheck Anti-Aliasing (I am not really sure this will help, but you can try...).